Surface-treated steel sheet, metal container, and method for producing surface-treated steel sheet

Abstract

There is provided a surface-treated steel sheet ( 1 ) comprising: a tin-plated steel sheet ( 10 ) obtained by tin-plating a steel sheet ( 11 ); a phosphate compound layer ( 20 ) containing tin phosphate formed on the tin-plated steel sheet ( 10 ); and an aluminum-oxygen compound layer ( 30 ) on the phosphate compound layer ( 20 ), a main constituent of the aluminum-oxygen compound layer ( 30 ) being an aluminum-oxygen compound; wherein, when the 3d 5/2 spectrum of tin in the aluminum-oxygen compound layer ( 30 ) is determined using an X-ray photoelectron spectroscopy, the ratio of the integration value of the profile derived from tin oxide to the integration value of the profile derived from tin phosphate (tin oxide/tin phosphate) is 6.9 or more.

The invention claimed is: 
     
       1. A method for producing a surface-treated steel sheet comprising:
 forming a phosphate compound layer on a tin-plated steel sheet by means of cathode electrolytic treatment, wherein the tin-plated steel sheet is obtained by tin-plating a steel sheet; and 
 forming an aluminum-oxygen compound layer on the phosphate compound layer by means of electrolytic treatment using an electrolytic treatment liquid containing aluminum, 
 wherein the electrolytic treatment liquid has a phosphate content of 0.11 g/L or less in terms of phosphorus atom and an aluminum ion content of 1 to 10 g/L in terms of aluminum atom, 
 the electrolytic treatment for forming the aluminum-oxygen compound layer is performed by an intermittent electrolysis method where a cycle of energization and stop of energization is repeated, and 
 a total energization time for forming the aluminum-oxygen compound layer is 1.5 seconds or less. 
 
     
     
       2. The method for producing a surface-treated steel sheet according to  claim 1 , wherein the phosphate compound layer is formed on the tin-plated steel sheet by means of the cathode electrolytic treatment after anode electrolytic treatment is conducted. 
     
     
       3. The method for producing a surface-treated steel sheet according to  claim 1 , wherein the phosphate compound layer is formed by immersing the tin-plated steel sheet in a treatment liquid containing phosphate ions to generate divalent tin ions from dissolved tin of the tin-plated steel sheet, and performing the cathode electrolytic treatment so that the divalent tin ions react with the phosphate ions so as to be deposited on the tin-plated steel sheet as tin phosphate.